I kind of worked backwards since I knew that the angle is 229 degrees (41 degrees clockwise from the -y axis). And I know that the x=-15. I took tan(229) which = 1.15, which should be the fraction of the y length over the x length. Since I know the x=-15 I just solved for y to get -13.0. And then I calculated the magnitude from that, which give me 19.8.

I thought this method would work, and I am not sure where I went wrong.